Did You Know...
...that when IBM conducted a market study of Chester Carlson's invention in 1959, the company concluded that it would take only 5000 units of his new product to saturate the market? IBM therefore declined to be part of the new product introduction. Too bad for IBM. Carlson's invention was the xerography process, and his new product was the beginning of the Xerox Corporation. It is estimated that every day, worldwide, 3,000,000,000 copies are made!!
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| Number | Title | Issue Date |
| 4275458 | Interrupt expander circuit An interrupt expander circuit provides for greatly enlarging the capacity of vectored interrupts in a microprocessor system. This circuit provides the capability for a very large number of peripheral devices to be connected to a microprocessor centeral pr... | 06/23/1981 |
| 4275272 | Remote time and charge system A remote time and charge system for use in conjunction with a telephone traffic service position system is shown. This system provides each hotel or motel with an automated print out of the duration of a particular call, the identity of the particular cal... | 06/23/1981 |
| 4274155 | Multiport conference circuit with multi-frame summing and voice level coding An improved conference circuit for use in a Pulse Code Modulation telephone switching system wherein a number of channels are combined so that a number of subscribers may participate in a common telephone conversation. The conference circuit is provided w... | 06/16/1981 |
| 4272140 | Arrangement for mounting dual-in-line packaged integrated circuits to thick/thin film circuits An arrangement for mounting a dual-in-line packaged integrated circuit (DIP) to a thick/thin film circuit wherein a portion of each DIP lead is formed into a U-shape including a horizontal foot portion. The arrangement further includes a complementary soc... | 06/09/1981 |
| 4272721 | Analog-to-digital converter alignment circuit A circuit for monitoring the alignment of analog-to-digital converters. The digital output signal from a converter under test is separated into positive and negative component signals which are compared by a subtraction circuit. A difference signal is the... | 06/09/1981 |
| 4270028 | Digitally activated ringing circuit for generation of AC voltages A digitally activated ringing circuit for use in conjunction with a central processing unit of an electronic telephone central office is connected between the central processing unit and a telephone subscriber via the central office switching network. The... | 05/26/1981 |
| 4270093 | Apparatus for forcing a phase-lock oscillator to a predetermined frequency when unlocked An active filter used for the loop filter of a phase-lock loop has one input to the operational amplifier thereof connected to receive the output from a phase detector, and has the non-inverting input connected to receive a control signal from an override... | 05/26/1981 |
| 4266103 | Key telephone exclusion circuit An exclusion circuit for use in a key telephone providing an exclusion release feature. Key telephones are excluded or prevented from accessing a busy line by the exclusion circuit. The exclusion release feature, in a key telephone connected to a telephon... | 05/05/1981 |
| 4257120 | Multiport conference circuit with multi-frame summing An improved conference circuit for use in a Pulse Code Modulation telephone switching system wherein a number of channels are combined so that a number of subscribers may participate in a common telephone conversation. The conference circuit is provided w... | 03/17/1981 |
| 4255624 | Call processing monitor system The present invention is a call processing monitor circuit for dynamically verifying the operation of a telephone switching center. This system provides for continuously testing a telephone switching center's ability to process telephone traffic. This is ... | 03/10/1981 |
| 4255634 | Cam actuated switching device A switching device comprising a spring pile-up assembly including a plurality of pairs of cantilevered stationary and movable contact springs secured between a pair of support members. A follower card is slidably mounted on the top portions of the support... | 03/10/1981 |
| 4255625 | Call processing monitor system The present invention is a call processing monitor circuit for dynamically verifying the operation of a telephone switching center. This system provides for continuously testing a telephone switching center's ability to process telephone traffic. This is ... | 03/10/1981 |
| 4255621 | Billing interface circuit A billing interface circuit for controlling the billing of a station of a private branch exchange via a telephone central office. This circuit automatically connects an intercept recorder to the operator requesting time and charges while providing ring ba... | 03/10/1981 |
| 4255618 | Digital intercept recorder/announcer system A digital intercept recorder/announcer system for use in conjunction with a telephone central office. The system performs the function of recorded message announcement for messages such as wrong number, time or weather announcements. The system samples an... | 03/10/1981 |
| 4252395 | Terminal apparatus for interconnecting two or more insulated electrical conductors Terminal apparatus comprised of an interconnecting terminal and an insulated base complementary to the terminal. The terminal includes a center section providing an electrical connection. The center section which includes slot-type termination devices is ... | 02/24/1981 |
| 4244018 | Interlock control of asynchronous data transmission between a host processor and a plurality of microprocessors through a common buffer An interlock circuit is set forth which provides for controlling asynchronous data transfers between a host processor and a plurality of microprocessors via a common buffer. The interlock circuit consists of an interconnection of latches arranged so that ... | 01/06/1981 |
| 4243841 | Digitally activated coin control circuit A digitally activated coin control circuit for use in combination with a digitally activated ringing circuit for common manipulation of a prepaid coin station by a central processing unit of a telephone switching center to collect and alternatively to ref... | 01/06/1981 |
| 4243847 | Automatic restoral mechanism for a pushbutton key telephone instrument A mechanism for automatically restoring an operated and depressed pushbutton line key in a multi-line key telephone instrument. When the telephone instruments handset is returned to the instruments cradle, the cradle rotates a cradle shaft which in turn r... | 01/06/1981 |
| 4240054 | Arrangement for locking a reed capsule within a magnetic latching reed switch assembly An arrangement for locking a reed capsule within a tubular bobbin of a reed switch assembly comprising, a deflectable tab located adjacent a slot formed by two upstanding arms. The tab is disposed to deflect inward when a wire return strap connected to a ... | 12/16/1980 |
| 4240024 | Temperature compensated current source An integrated current source comprising a discrete resistor having one side thereof electrically connected through a PNP transistor to a first DC supply voltage and through series connected base-emitter diodes of a first pair of NPN transistors to a tempe... | 12/16/1980 |
| 4239941 | Ringing signal generator A telephone ringing signal generator which produces a signal that can ring a plurality of connected ringers tuned to different frequencies. The ringing signal comprises sequentially varying frequencies and each ringer will ring in response to its particul... | 12/16/1980 |
| 4238655 | Cam actuated switching device A switching device comprising a spring pileup assembly including a plurality of pairs of cantilevered stationary and movable contact springs secured between a pair of support members. A follower card is slidably mounted on the top portions of the support ... | 12/09/1980 |
| 4238645 | Variable loop telephone transmission circuit A subscriber station telephone circuit having a multiwinding transformer connected in a bridge configuration to couple the transmitter to the line and the balancing impedance in opposite phase. The receiver is magnetically coupled by the transformer so as... | 12/09/1980 |
| 4234957 | Method and apparatus for generating timing phase error signals in PSK demodulators A circuit arrangement for combining a measure of the single phase error for a received data signal in a PSK demodulator with a measure of the direction of rotation of the receive data signal phasor between adjacent sample times for producing a timing phas... | 11/18/1980 |
| 4234953 | Error density detector An error detector provides an output pulse whenever an error is detected in the framing pattern of a digital transmission system. A sample timer provides a sample pulse at the beginning of each sample interval and a sample clock pulse during the sample pu... | 11/18/1980 |
| 4230912 | Dial pulse sensor and repeater circuit A line voltage sensor and dial pulse repeater circuit for use in conjunction with a digital PABX telephone system connecting a subscriber station to a switching center providing for detection of off-hook condition of the subscriber's set, detection of irr... | 10/28/1980 |
| 4229665 | Programmable power supply system A programmable power supply system which supplies all of the power requirements of a telephone subscriber's loop circuit in a digital telephone switching system. An associated processing unit generates digital control signals to select a particular power ... | 10/21/1980 |
| 4226932 | Titanium nitride as one layer of a multi-layered coating intended to be etched A multilayered thin film structure comprising layers of resistive and conductive materials on a substrate, said layers including tantalum nitride, palladium and gold. A layer of titanium nitride, is used between the tantalum nitride and palladium layers t... | 10/07/1980 |
| 4222020 | Control winding for a magnetic latching reed relay A magnetic latching reed relay including a single continuous control winding disposed about an encapsulated reed switch having a pair of reeds constructed of a remanent magnetic material. The reeds are normally biased in an open position. When a first pul... | 09/09/1980 |
| 4219697 | Automatic remote operate circuit A device for the remote turn on of a teletypewriter of a distant terminal, such as at a hotel or motel. The turn on circuit is connected to the communication line to operate a magnetically latching relay. The latching relay operates to turn on the alterna... | 08/26/1980 |
| 4209218 | Insulated electrical conductor locking arrangement and method An arrangement and method for locking an insulated electrical conductor to a slot-type terminal wherein a locking device is molded as part of the terminal base. As an insulated electrical conductor to be terminated is pushed into the slot-type terminal wi... | 06/24/1980 |
| 4207534 | Fast redundant pulse density analyzer A self-checking pulse density analyzer includes substantially similar first and second threshold detection circuits, each of which have one input connected to receive incoming pulse information to be analyzed, and each of which provide the same binary sig... | 06/10/1980 |
| 4207436 | Constant percent break type dial pulse corrector The first monostable multivibrator of a series connected pair of monostable multivibrators is responsive to each break interval of input dial pulses for establishing a fixed time delay after which the second multivibrator initiates a corrected break inter... | 06/10/1980 |
| 4205275 | Method and apparatus of controlling bias voltage in regulating amplifiers A regulating amplifier circuit with each transistor of a differentially connected pair thereof having a base electrode connected through an associated varistor to a first control transistor, the series combination of each varistor and the control transist... | 05/27/1980 |
| 4203510 | Pneumatic diverter for hybrid thick film substrate processing equipment In a thick film screen printer having a chute that is alternately in a horizontal position for receiving a screened substrate at one location on it and inclined downward to slide the screened substrate onto a conveyor belt, a pair of elongated openings ex... | 05/20/1980 |
| 4204241 | Low power consumption relay switching circuit for use in conjunction with a line test trunk interfacing to a test desk An improved circuit for interfacing between a test desk, a subscriber line and an electronic switching center is disclosed herein. The disclosed improvements allow the relay circuit to operate in response to a predetermined threshold current value while r... | 05/20/1980 |
| 4203003 | Frame search control for digital transmission system A frame search control circuit for a digital transmission system includes an eight bit preview store and a four stage counter. At the beginning of each frame a timing device causes the eight stored bits to be sequentially read out into a comparator for a ... | 05/13/1980 |
| 4201894 | Arrangement for conversion of random to fixed data channel format A private automatic branch exchange employing time division switching of digital signals, with provision for interfacing a fixed format data channel source to the randomly assigned channel allocation of the exchange. This is accomplished via channel buffe... | 05/06/1980 |
| 4201893 | Private automatic branch exchange telephone system with two data sources sharing a multiplexed data bus Groups of analog trunks are shown connected to analog to digital converters. The converters are each assigned a time during which their associated trunks may access a common data bus to the pulse code time division switching system. Provision is made for ... | 05/06/1980 |
| 4201885 | Routinable clock circuit A routinable clock circuit for use in an automatic identification of outward dialing (AIOD) system. The clock circuit consists of asynchronous receive and transmit portions connected and utilized in such a manner as to permit a central processing unit to ... | 05/06/1980 |
